1. Field of the Invention
The present invention relates to a method for replacing an existing telephone switching center with a new telephone switching center, and is more particularly concerned with the testing of line connections before switching over from the old switching center to the new switching center.
2. Description of the Prior Art
As mentioned above, the present invention is directed to a method for testing a line connection before switching from a telephone switching center (old switching center) to be taken out of service to a digital telephone switching center (new switching center) to be newly placed into operation. The line termination circuits of the system contain test circuit contacts, of which one serves the purpose of connecting the line termination accessible via a main distributor to a bus shared by all line termination circuits of at least one group of line input/output circuits and a further test circuit contact serving the purpose of connecting the line termination to the further components of the line input/output circuit. The system further contains tone generators shared by groups of line termination circuits for generating what are, above all, switching-oriented call progress tones and code receivers for selection signals and other signals that can be assigned, as needed, to the line termination circuits, as well as two special termination circuits largely corresponding to the line termination circuits in terms of function by way of which selection information can be output just as from a terminal equipment.
In a switching system of the type set forth above, the subscriber lines are disconnected from the old switching center and are connected to the new switching center at a main distributor, which is already prepared for this purpose by separating connecting bridges or, respectively, by attaching new connecting bridges. It must be assured in such a rewiring that the same subscriber number remains assigned to the terminal equipment. A test must also be carried out to see whether the correct assignment of the database to the individual subscriber connections is established in the new switching center.
A manual method that was heretofore practiced for testing of the line connection shall be set forth in greater detail below with reference to FIG. 1.
With respect to the prior art, FIG. 1 illustrates an old or existing switching center AV and a new switching center NV, each having subscriber line input/output 0-N to which subscriber terminal equipment T1n0-T1nN are connected or, respectively, can be connected via subscriber lines and via a main distributor HV. For each subscriber line is provided a subscriber line termination circuit through which signals are input and output between the subscriber line and the main distributor. A plurality of connection bridges is provided by way of which the connection of the subscriber terminal equipment or, respectively, of the subscriber line termination circuits of the subscriber lines to the old switching center AV is provided, the connection bridges being referenced IA0-IAN, which are plugged into the main distributor HV. The connection bridges IN0-INN must be plugged for connecting the subscriber terminal equipment to the new switching center.
In addition to the connection for the subscriber lines input/output, the two switching centers each respectively comprise a test connection input/output T, by way of which the connected subscriber terminal equipment can be selected by inputting selection information. Testing equipment MBTE is connected to these test connection input/output in the present example. With the assistance of a test plug P that can be plugged instead of the switching bridges IN0-INN, inputs of the testing equipment can be connected both to a line termination circuit via the old switching center AV as well as to a line termination circuit via the new switching center NV. The speakers of a headset EPh are electrically connected to these inputs.
For testing the line connection, the test plug P is then plugged instead of the switching bridge that connects to a line input/output of the new switching center NV and the subscriber number corresponding to the terminal is selected with the assistance of the testing equipment MBTE. A connection from the test connection input/output to the appertaining line termination circuit is therefore produced via the old switching center, as well as via the new switching center. This set-up of connections occurring via the test connection input/output is of such a nature that the appertaining subscriber terminal equipment does not receive a call. The testing equipment now transmits a test tone to both switching centers and the operator checks via the headset EPh whether this test tone can be received by the subscriber lines of both switching centers. Insofar as this is not the case, a check of the wiring that has been undertaken in the main distributor must be undertaken or, respectively, a check of the assignment of the data base to the appertaining line termination must be undertaken.
When all line inputs/outputs have been checked and found to be correct, the switching bridges IA0-IAN that connect to the old switching center AV are pulled (disconnected) and the switching bridges IN0-INN that connected to the new switching center NV are plugged in.
This testing procedure requires a considerable amount of time and effort.